. >> reporter: bob's phone is packed with personal files. >> people use their phones for tracking health information, financial information, for talking with their bosses or talking about their bosses. >> reporter: in january of last year, he was arrested during a peaceful pro-fest advocating for homeless lights. police legally got ahe would of his phone and his information. >> they took my phone and read my text messages. i asked what are you doing? they said we're reading your messages. and i said i don't consent to that. >> reporter: a california supreme court decision says if you are under arrest, police can search your phone. he believes police should be required to get a warrant before looking inside. and he's doing the leg work to try and make it happen. teaming up with the acla, filing a lawsuit against san francisco and the police chief. the aclu says this chamgs the previous court decision by asking the court to consider constitutional protections. >> we have protections in the federal and state constitutions for speech and association. >> reporter: it will be up to the court t